The main objective of this research is to understand the molecular mechanics of the "interfacial activation" of soluble phospholipases. We are using NMR and other physical techniques to investigate phospholipid interactions with phospholipase-A2, (Naja naja naja) phospholipase-C, (Bacillus cereus) and phospholipase-D (cabbage). Specific problems being addressed are: (1) conformation/orientation changes between monomer and aggregated phospholipid; (2) physical basis for surface dilution kinetics; (3) kinetic role (if any) of phospholipase aggregation; and (4) identification and characterization of multiple phospholipid sites in phospholipases.